Method and apparatus for the curing of composite material by control over rate limiting steps in water removal

ABSTRACT

The invention encompasses equipment used to condition a recirculating gas stream in order to cure a CO 2  Composite Material (CCM) and processes that use such equipment to cure the CCM. The gas conditioning equipment allows for a process that controls, reduces or eliminates the rate-limiting steps associated with water removal during the curing of a composite material. The equipment may include, but will not be limited to, control over the temperature, relative humidity, flow rate, pressure, and carbon dioxide concentration within the system; which includes the conditioning equipment, any vessel containing the CCM, and the material itself. Flow rate control can be used as a means to achieve uniformity in both gas velocity and composition.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation-in-part of co-pending U.S. patentapplication Ser. No. 14/602,313, filed Jan. 22, 2015, which applicationclaims priority to and the benefit of then U.S. provisional patentapplication Ser. No. 61/930,404, filed Jan. 22, 2014, and claimspriority to and the benefit of U.S. provisional patent application Ser.No. 62/033,366, filed Aug. 5, 2014, each of which applications isincorporated herein by reference in its entirety, and is acontinuation-in-part of co-pending U.S. patent application Ser. No.14/209,238, filed Mar. 13, 2014, which application claims priority toand the benefit of then U.S. provisional patent application Ser. No.61/785,226, filed Mar. 14, 2013.

FIELD OF THE INVENTION

The invention relates to systems and methods for curing compositematerials in general and particularly to systems and methods thatcontrol the water content of the composite as it cures.

BACKGROUND OF THE INVENTION

Curing chambers for many systems of materials are known in the art,including chambers that are configured to handle materials undergospecific chemical reactions. Some of the problems that are associatedwith conventional curing chambers include their cost, their limitationsas regards operating conditions and locations, and the precision withwhich the curing process may be controlled.

There is a need for curing chambers and methods that provideversatility, precision and reduced costs.

SUMMARY OF THE INVENTION

According to one aspect, the invention features a curing system forcuring a material which requires CO₂ as a curing reagent. The materialdoes not cure in the absence of CO₂. The material does not consume wateras a reagent. The curing system comprises a curing chamber configured tocontain a material that consumes CO₂ as a reactant (or reagent) and thatdoes not cure in the absence of CO₂. The curing chamber has at least oneport configured to allow the material to be introduced into the curingchamber and to be removed from the curing chamber, and has at least oneclosure for the port, the closure configured to provide an atmosphericseal when closed so as to prevent (or to limit to an innocuous level)contamination of a gas present in the curing chamber by gas outside thecuring chamber; a source of carbon dioxide configured to provide gaseouscarbon dioxide to the curing chamber by way of a gas entry port in thecuring chamber, the source of carbon dioxide having at least one flowregulation device configured to control a flow rate of the gaseouscarbon dioxide into the curing chamber; a gas flow subsystem configuredto circulate the gas through the curing chamber during a time periodwhen the material that consumes CO₂ as a reactant is being cured; atemperature control subsystem configured to control a temperature of thegas within the chamber; a humidity control subsystem configured tocontrol a humidity in the gas within the chamber to increase or decreasehumidity; and at least one controller in communication with at least oneof the source of carbon dioxide, the gas flow subsystem, the temperaturecontrol subsystem, and the humidity control subsystem; and at least onecontroller configured to control independently during a time period whenthe material that consumes CO₂ as a reactant is being cured at least arespective one of the flow rate of the gaseous carbon dioxide, thecirculation of the gas through the curing chamber, the temperature ofthe gas, and the humidity in the gas.

According to one aspect, the invention features a curing system forcuring a material to be cured by reaction with carbon dioxide. Thecuring system comprises a gas conditioning system and a curing chamberconnected together by a gas delivery tube and a gas recovery tube, thecuring chamber configured to contain the material to be cured byreaction with carbon dioxide; the gas conditioning system including asource of carbon dioxide, a gas flow subsystem, a temperature controlsubsystem, a humidity control subsystem and a subsystem for controllingthe curing process parameters; the subsystem for controlling the curingprocess parameters comprising a controller having a microprocessorconfigured to operate under the control of a set of instructionsrecorded on a first machine-readable medium so as to control a curingprocess of the material to be cured by reaction with carbon dioxide.

According to one aspect, the invention features a controller. Thecontroller comprises a microprocessor configured to operate under thecontrol of a set of instructions recorded on a first machine-readablemedium, the microprocessor when operating under the set of instructionsperforming the following steps: controlling the operation of at leastone of a source of carbon dioxide, a gas flow subsystem, a temperaturecontrol subsystem, and a humidity control subsystem; instituting a flowof a process gas containing carbon dioxide so as to contact a materialto be cured by reaction with the carbon dioxide in the process gas;monitoring at least one parameter selected from the group of parametersconsisting of an elapsed time from the instituting of the flow, a carbondioxide concentration, a relative humidity, a flow rate, a temperature,and a pressure of the process gas as the process gas is being provided;and performing at least one of recording at least one of the monitoredparameters, transmitting the at least one of the monitored parameters toa data handling system, or to displaying the at least one of themonitored parameters to a user.

In one embodiment, the microprocessor when operating under the set ofinstructions performs the step of receiving a start command from anexternal source.

In another embodiment, the microprocessor when operating under the setof instructions performs the step of determining whether a curingchamber is properly loaded.

In yet another embodiment, the microprocessor when operating under theset of instructions performs the step of determining whether a curingchamber is properly closed.

In still another embodiment, the microprocessor when operating under theset of instructions performs the step of determining a state of cure ofthe material to be cured by reaction with the carbon dioxide.

In a further embodiment, the microprocessor when operating under the setof instructions performs the step of monitoring at least one parameterselected from the group of parameters consisting of a carbon dioxideconcentration, a relative humidity, a flow rate, a temperature, apressure, and a flow duration of the process gas as the process gas isremoved from contact with the material to be cured by reaction with thecarbon dioxide.

In yet a further embodiment, the microprocessor when operating under theset of instructions performs the step of monitoring at least oneparameter selected from the group of parameters consisting of a carbondioxide concentration, a relative humidity, a flow rate, a temperature,and a pressure at one or more locations within a curing chamber.

In an additional embodiment, the microprocessor when operating under theset of instructions performs the step of receiving input from a userrepresenting one or more process parameters constituting a step of aprocess to be performed.

In one more embodiment, the microprocessor when operating under the setof instructions performs the step of recording in a non-volatile machinereadable medium the input from the user as a step in a process recipe.

In still a further embodiment, the microprocessor when operating underthe set of instructions performs the step of retrieving at least onestep of a process recipe recorded on a non-volatile machine readablemedium.

In one embodiment, the first machine readable medium and thenon-volatile machine readable medium are the same medium.

According to another aspect, the invention relates to a gas flowsubsystem. The gas flow subsystem comprises at least one of a valve, aflow regulator, a mass flow controller, a blower, and a gas deliverystructure; the gas flow subsystem configured to provide a process gascomprising carbon dioxide as a reagent in fluid contact with a materialto be cured by reaction with the carbon dioxide.

In one embodiment, the gas flow subsystem is compatible with water vaporin addition to the process gas comprising carbon dioxide as a reagent.

In another embodiment, the gas flow subsystem is compatible with air inaddition to the process gas comprising carbon dioxide as a reagent.

In yet another embodiment, the gas delivery structure is embedded in thematerial to be cured by reaction with the carbon dioxide.

In still another embodiment, the gas delivery structure is a gaspermeable layer placed adjacent the material to be cured by reactionwith the carbon dioxide.

In a further embodiment, the gas flow subsystem further comprises acommunication port configured to receive control signals from acontroller.

In yet a further embodiment, the gas flow subsystem further comprises acommunication port configured to communicate to a controller a signalencoding at least one of a carbon dioxide concentration, a relativehumidity, a flow rate, a temperature, and a pressure of the process gas.

In an additional embodiment, the gas flow subsystem further comprises agas recovery tubulation.

In one more embodiment, the gas flow subsystem further comprises acommunication port configured to communicate to a controller a signalencoding at least one of a carbon dioxide concentration, a relativehumidity, a flow rate, a temperature, and a pressure of a gas present inthe gas recovery tubulation.

According to another aspect, the invention relates to a temperaturecontrol subsystem. The temperature control subsystem, comprises at leasta selected one of a heater and a cooler, the temperature controlsubsystem configured to control a temperature of a process gascontaining carbon dioxide so as to cause the process gas to attain adesired temperature prior to coming into contact with a material to becured by reaction with the carbon dioxide in the process gas.

In one embodiment, the temperature control subsystem further comprises asensor configured to measure a gas temperature.

In another embodiment, the sensor is a thermocouple.

In yet another embodiment, the temperature control subsystem furthercomprises a sensor configured to measure a relative humidity.

In still another embodiment, the temperature control subsystem furthercomprises a communication port configured to communicate a signalrepresenting at least one of a temperature value and a relative humidityvalue to a controller.

In a further embodiment, the temperature control subsystem furthercomprises a communication port configured to receive a control signalfrom a controller.

In yet a further embodiment, the temperature control subsystem isconfigured to employ the control signal to cause the at least a selectedone of the heater and the cooler to operate.

According to another aspect, the invention relates to a humidity controlsubsystem. The humidity control subsystem, comprises at least a selectedone of a water vapor source and a water vapor removal apparatus, thehumidity control subsystem configured to control a humidity of a processgas containing carbon dioxide so as to cause the process gas to attain adesired humidity prior to coming into contact with a material to becured by reaction with the carbon dioxide in the process gas.

In one embodiment, the water vapor source comprises a source of water, avalve and a spray head.

In another embodiment, the water vapor source comprises a steamgenerator.

In yet another embodiment, the steam generator comprises a submersibleheater.

In another embodiment, the water vapor source comprises a bubblercontaining water through which a gas may be bubbled.

In yet another embodiment, the water vapor removal apparatus is achiller.

In still another embodiment, the water vapor removal apparatus is acondenser.

In yet another embodiment, the water vapor removal apparatus is a heatexchanger.

In a further embodiment, the humidity control subsystem furthercomprises a humidity sensor configured to measure a relative humidity ofthe process gas.

In yet a further embodiment, the humidity control subsystem furthercomprises a communication port configured to communicate a signalrepresenting the relative humidity value to a controller.

In an additional embodiment, the humidity control subsystem furthercomprises a communication port configured to receive a control signalfrom a controller.

In one more embodiment, the humidity control subsystem is configured toemploy the control signal to cause the at least a selected one of thewater vapor source and the water vapor removal apparatus to operate.

According to one aspect, the invention features a curing chamber. Thecuring chamber comprises an enclosure defining an enclosed volume, theenclosure comprises a wall configured to contain a material to be curedby reaction with carbon dioxide in a process gas, the enclosurecomprises a closeable opening configured to allow the material to becured to be introduced into the enclosure; an inlet port configured toallow the process gas containing carbon dioxide to enter the enclosure;and an outlet port configured to allow the process gas to exit theenclosure.

In one embodiment, the curing chamber further comprises a plenumsituated within the enclosure, the plenum configured to provide theprocess gas by way of one or more locations at which the process gas canbe injected into the enclosure.

In another embodiment, the plenum is configured to control at least oneof a flow velocity, a flow direction, and a flow pattern of the processgas in the enclosure.

In yet another embodiment, the plenum is configured to direct a flow ofthe process gas to at least one of an outside of the material to becured and to an internal passage defined in the material to be cured.

In still another embodiment, the inlet port is configured to control atleast one of a flow velocity, a flow direction, and a flow pattern ofthe process gas in the enclosure.

In a further embodiment, the outlet port is configured to control atleast one of a flow velocity, a flow direction, and a flow pattern ofthe process gas in the enclosure.

In yet a further embodiment, the wall is a flexible wall.

In an additional embodiment, the flexible wall is fabricated from aselected one of plastic, Mylar® and latex.

In one more embodiment, the flexible wall includes a coating configuredto retain thermal energy.

In still a further embodiment, the wall includes an aperture coveredwith a material that is transparent in a spectral region of interest.

In one more embodiment, at least one sensor is present within theenclosure, the at least one sensor configured to provide data about atleast one of a property of the process gas and an operating conditionwithin the enclosure.

According to another aspect, the invention relates to a cast-in-placemethod. The cast-in-place method comprises the steps of: preparing alocation at which a material to be cured by reaction with carbon dioxidein a process gas is to be situated; placing a process gas deliverystructure and the material to be cured by reaction with carbon dioxidein the prepared location; and providing the process gas to the materialto be cured by way of the process gas delivery structure for a timeperiod sufficiently long to effect a cure of the material to be cured.

In one embodiment, the process gas delivery structure remains with thematerial to be cured after the curing process is completed.

In another embodiment, the cast-in-place method further comprises thestep of covering the process gas delivery structure and the material tobe cured by reaction with carbon dioxide after they are placed in theprepared location.

In yet another embodiment, the step of providing the process gasincludes controlling a parameter of the process gas selected from thegroup of parameters consisting of an elapsed time from the institutingof the flow, a carbon dioxide concentration, a relative humidity, a flowrate, a temperature, and a pressure of the process gas as the processgas is being provided.

In still another embodiment, the cast-in-place method further comprisesthe step of controlling an amount of water present in the material to becured by reaction with carbon dioxide.

In a further embodiment, the step of controlling an amount of waterpresent in the material to be cured comprises a selected one of removingwater from the material or adding water to the material.

The foregoing and other objects, aspects, features, and advantages ofthe invention will become more apparent from the following descriptionand from the claims.

BRIEF DESCRIPTION OF THE DRAWINGS

The objects and features of the invention can be better understood withreference to the drawings described below, and the claims. The drawingsare not necessarily to scale, emphasis instead generally being placedupon illustrating the principles of the invention. In the drawings, likenumerals are used to indicate like parts throughout the various views.

FIG. 1 is a schematic diagram of an embodiment of a curing system foruse with CO₂ Composite Material.

FIG. 2 is a schematic diagram of an embodiment of an alternate curingsystem for use with CO₂ Composite Material.

FIG. 3 is a perspective view of a curing chamber suitable for curingelongate specimens of CO₂ Composite Material.

FIG. 4 is a view of the curing chamber of FIG. 3 containing an elongatespecimen of CO₂ Composite Material to be cured.

FIG. 5 is a view of the curing chamber of FIG. 3 when closed to allowcuring to be performed.

FIG. 6 is an image of a plenum used to deliver a curing atmosphere to asample of CO₂ Composite Material having an interior circular channel.

FIG. 7 is an image of a sample of CO₂ Composite Material that was curedusing flow in an interior circular channel.

FIG. 8 is an image that illustrates the difference in reaction depth asa function of flow rate.

FIG. 9 is a graph that illustrates the differences in reaction depth,gas flow in cubic feet per minute and amount of water removed fromspecimens of CO₂ Composite Material cured in systems using 1 fan and 3fans.

FIG. 10 is a graph showing data for water removal rate as a function offlow rate for gases having different relative humidity.

FIG. 11 is a process flow chart illustrating the steps in a process ofplacing and curing a composite material in an outdoor location.

FIG. 12 is an image that illustrates a perforated PVC grid used for gasdelivery to a cast-in-place section of pervious CO₂ Composite Material.

FIG. 13 is an image that illustrates pervious CO₂ Composite Materialbeing poured over the gas delivery system of FIG. 12.

FIG. 14 is an image that illustrates a section of pervious CO₂ CompositeMaterial that is covered with plastic sheeting and that has a CO₂ inletconnected thereto.

FIG. 15 is an image that shows gas flow regulators and a flow meter usedto control the CO₂ supply to the pervious CO₂ Composite Material sectionof FIG. 14.

FIG. 16 is an image that shows a cured section of pervious CO₂ CompositeMaterial after 22 hours using the embedded CO₂ delivery system of FIG.12.

FIG. 17 is a process flow chart illustrating the steps of placing andcuring CO₂ Composite Material using the cast-in-place process.

FIG. 18 is an image showing a mold that allows CO₂ delivery to andthrough Enkavent® material.

FIG. 19 is an image showing uncured CO₂ Composite Material mix for usein a cast-in-place process.

FIG. 20 is an image showing a mold 1800 after casting a CO₂ CompositeMaterial and connection of the process gas line for curing the CO₂Composite Material with CO₂.

FIG. 21 is an image showing a section cut from a slab of CO₂ CompositeMaterial after carbonation curing.

FIG. 22 is a view of a curing chamber made of flexible material.

FIG. 23 is a view of the flexible material being installed to form thecuring chamber of FIG. 22.

FIG. 24 is a view of a clamping method for holding the flexible materialof the curing chamber of FIG. 22 to a rigid support.

FIG. 25 is a view of another embodiment of a curing chamber having someflexible walls and some relatively rigid walls.

FIG. 26 is a view of a modular gas handling system that can be used withvarious curing chambers.

FIG. 27 is a schematic diagram showing a gas handling system that hasmultiple gas delivery ports and multiple gas recovery ports.

FIG. 28 is a screenshot of a computer based control system for a curingchamber showing a schematic of the system to be controlled.

FIG. 29 is a screenshot of a computer based control system for a curingchamber showing a number of components that can be controlled andshowing how parameter values that are measured can be displayed.

FIG. 30 is a screenshot of a computer based control system for a curingchamber showing a recipe screen in which parameters for various periodsor steps in a curing process can be entered by a user or displayed to auser.

FIG. 31 is a screenshot image of an historical trend report for a curingoperation, showing a graph 3100 in which curve 3110 represents total CO₂consumed, curve 3120 represents relative humidity, and curve 3130represents temperature.

DETAILED DESCRIPTION

The invention relates to methods of processing or “curing” compositematerials by means of controlling the atmospheric conditions in andaround the material in a precise manner; as well as the equipmentinvolved in doing so.

INCORPORATION BY REFERENCE

Any patent, patent application, patent application publication, journalarticle, book, published paper, or other publicly available materialidentified in the specification is hereby incorporated by referenceherein in its entirety. Any material, or portion thereof, that is saidto be incorporated by reference herein, but which conflicts withexisting definitions, statements, or other disclosure materialexplicitly set forth herein is only incorporated to the extent that noconflict arises between that incorporated material and the presentdisclosure material. In the event of a conflict, the conflict is to beresolved in favor of the present disclosure as the preferred disclosure.

CO₂ Composite Material

The present invention relies in part on the use of materials thatundergo curing in the presence of carbon dioxide (CO₂) that can besupplied in gaseous form and that is believed to be active in hydratedform (e.g., as a water soluble carbonate derived from H₂CO₃). The curedmaterials that result from such processes will be referred tocollectively herein as “CO₂ Composite Material” (“CCM”) or “CO₂Composite Materials” (“CCMs”). The chemistry and preparation of variouskinds of CO₂ Composite Material has been described in various patentdocuments, including U.S. Patent Application Publication No. 20140127450A1, published May 8, 2014 and U.S. Patent Application Publication No.20140127458 A1, published May 8, 2014.

The CO₂ Composite Materials may exhibit aesthetic visual patterns aswell as display compressive strength, flexural strength and waterabsorption similar to that of the corresponding natural materials. TheCO₂ Composite Materials can be produced using the efficient gas-assistedhydrothermal liquid phase sintering (HLPS) process at low cost and withmuch improved energy consumption and carbon footprint. In fact, inpreferred embodiments of the process, CO₂ is consumed as a reactivespecies resulting in net sequestration of CO₂.

The CO₂ Composite Materials can be made to display various patterns,textures and other characteristics, such as visual patterns of variouscolors. In addition, the CO₂ Composite Materials exhibit compressivestrength, flexural strength and water absorption properties similar toconventional concrete. The CO₂ Composite Materials can be cured to apoint where they are ready for use in time intervals (such as hours)that are often considerably reduced from the times required to cureconventional concrete (such as days to weeks). Furthermore, the CO₂Composite Materials can be produced using the energy-efficient HLPSprocess and can be manufactured at low cost and with favorableenvironmental impact. For example in preferred embodiments of theinvention, CO₂ is used as a reactive species resulting in sequestrationof CO₂ in the produced CO₂ Composite Materials with in a carbonfootprint unmatched by any existing production technology. The HLPSprocess is thermodynamically driven by the free energy of the chemicalreaction(s) and reduction of surface energy (area) caused by crystalgrowth. The kinetics of the HLPS process proceed at a reasonable rate atlow temperature because a solution (aqueous or nonaqueous) is used totransport reactive species instead of using a high melting point fluidor high temperature solid-state medium.

Discussions of various aspects of HLPS can be found in U.S. Pat. No.8,114,367, U.S. Pub. No. US 2009/0143211 (Applications. Ser. No.12/271,566), U.S. Pub. No. US 2011/0104469 (Applications. Ser. No.12/984,299), U.S. Pub. No. 20090142578 (Applications. Ser. No.12/271,513), WO 2009/102360 (PCT/US2008/083606), WO 2011/053598(PCT/US2010/054146), WO 2011/090967 (PCT/US2011/021623), U.S.application Ser. No. 13/411,218 filed Mar. 2, 2012 (Riman et al.), U.S.application Ser. No. 13/491,098 filed Jun. 7, 2012 (Riman et al), U.S.Provisional Patent Application No. 61/708,423 filed Oct. 1, 2012, andU.S. Provisional Patent Application Nos. 61/709,435, 61/709,453,61/709,461, and 61/709,476, all filed Oct. 4, 2012, each of which isexpressly incorporated herein by reference in its entirety for allpurposes.

The terms “rate-limiting step” or “rate limiting steps” refer to one ormore steps that are restricting or controlling the time a carbonationreaction takes.

Flow is the movement of gas described as a velocity and/or volume, usingvelocity in fps (feet per second) or volumetrically as cfm (cubic feetper minute).

The term “temperature” or “temperature range” represents one or more ofthe overall internal system temperature, a gas temperature, and a sampletemperature.

The term “relative humidity” represents the ratio of the partialpressure of water vapor in a gas in the system to the saturated vaporpressure of water in that gas at a certain temperature, which may varythroughout the system.

The term “CO₂ concentration” represents the amount of CO₂ in a systemdivided by the total volume of gas in that system, expressed as apercentage.

The invention contemplates a process that maximizes the carbonation rateof a composite material by controlling the drying rate of that material.The process can include a carbonation duration is between 0 and 1,000hours. The process can include a CO₂ Composite Material that has apermeability in the range of 0% and 100%. The process can include a CO₂Composite Material that has a carbonation depth of the CCM in the rangeof 0 and 36 inches. The process can include a CO₂ Composite Materialwherein the amount of water removed from the CCM is equal to between 0%and 99% of the CCM mass.

The invention encompasses the equipment used to condition arecirculating gas stream in order to cure a CCM and processes that usesuch equipment to cure the CCM. The gas conditioning equipment allowsfor a process that controls, reduces or eliminates the rate-limitingsteps associated with water removal during the curing of a compositematerial. The equipment may include, but will not be limited to, controlover the temperature, relative humidity, flow rate, pressure, and carbondioxide concentration within the system; which includes the conditioningequipment, any vessel containing the CCM, and the material itself. Flowrate control can be used as a means to achieve uniformity in both gasvelocity and composition.

The equipment can comprise various subsystems. The subsystems caninclude a curing chamber, a source of carbon dioxide, a gas flowsubsystem, a temperature control subsystem, a humidity controlsubsystem, and a controller in communication with at least one of thesource of carbon dioxide, the gas flow subsystem, the temperaturecontrol subsystem, and the humidity control subsystem; and at least onecontroller configured to control independently during a time period whenthe material that consumes CO₂ as a reactant is being cured at least arespective one of the flow rate of the gaseous carbon dioxide, thecirculation of the gas through the curing chamber, the temperature ofthe gas, and the humidity in the gas.

Curing Chambers

Various types of curing chambers and apparatus can be employed forcuring CCMs. Some curing chambers and apparatus may be provided inpermanent or semi-permanent facilities, while others may be used for atime (e.g., temporary installation) and some may be used once (e.g.,curing a CCM in place, for example at some out-of-doors location, suchas curing a CCM for form a slab for a walkway, a driveway, a road, alanding strip, or a support slab for a structure). FIG. 1 and FIG. 2 areschematic diagrams of embodiments of a curing system for use with CO₂Composite Material.

In some embodiments, the chamber or enclosure itself may be designed forone or a few repetitions of a curing process, or may be designed to lastfor an indefinitely long number of repetitions of a curing process. Insome embodiments, the relative cost of the chamber as compared to thevalue of the product being cured will serve as a guide as to thematerials and methods of construction of the chamber or enclosure.

Source of Carbon Dioxide

Carbon dioxide may be provided from any convenient source that cansupply sufficient gas quantities at high enough purity. In someembodiments, the source of carbon dioxide is gas generated from liquidcarbon dioxide. In some embodiments, the source of carbon dioxide is gasprovided in the form of gas in a high pressure cylinder. In someembodiments, the source of carbon dioxide is effluent from a combustionsystem that is processed to provide a supply of purified carbon dioxide.

Gas Flow Subsystem

In some embodiments there is provided a gas flow subsystem for providingthe necessary gases (e.g., CO₂, water vapor, air, and possibly othergases) that are useful for curing a CCM. The gas flow system includes ascomponents one or more of valves, flow regulators, mass flowcontrollers, and blowers that are suitable for causing gas flows atdesired flow rates (e.g., suitable mass per unit of time), desiredpressures, and desired compositions (e.g., ratios or proportions ofcarbon dioxide to water to air and possibly other gases). The curingchamber can further include structures that control the flow rates andflow directions in the curing chamber, as well as the physical locationsof gas inlets and outlets.

Temperature Control Subsystem

In some embodiments there is provided a temperature control subsystemthat allows the provision of gas having desired gas temperature. Thetemperature control subsystem can be useful to control reaction rates asa function of temperature, as well as operational parameters such asrelative humidity that have a temperature dependence. The temperaturecontrol system can comprise one or more heaters, one or more coolers,one or more sensors configured to measure a gas temperature at alocation, and a communication port configured to communicate with acontroller. In some embodiments, the communication is unidirectional,for example communication in which the controller sends a control signalto control the temperature control subsystem by causing at least one ofthe heater and the cooler to operate. In other embodiments, thecommunication is unidirectional, in which the temperature control systemsends signals representing parameters such temperature and relativehumidity to a controller. In some embodiments, signals can becommunicated in both directions.

Humidity Control Subsystem

In some embodiments there is provided a humidity control subsystem thatallows the control of the relative humidity in the process gas used inthe system. The humidity control subsystem can be used to add watervapor to the process gas that is supplied to the curing chamber if therelative humidity is too low or if one wishes to add water to a CCMduring the curing process, and it can be used to remove water vapor fromprocess gas that exits or is exhausted from the curing chamber if therelative humidity is too high or if one wishes to extract water from aCCM during the curing process. For example, the apparatus to add watervapor can be a source of water, a valve, and a spray head or spraynozzle. In another embodiment, the apparatus to add water vapor can be asteam generator. The steam generator can include a submersible heater.In other embodiments, water vapor can be added by bubbling a gas througha water bubbler. The apparatus to remove water can be a chiller, acondenser or a heat exchanger. The humidity control subsystem includeshumidity sensors that can measure the reactive humidity of the processgas at various locations in the gas flow systems, such as at thelocation where process gas enters or exits the curing chamber, and asappropriate, at other locations in the curing chamber or in the gas flowsubsystem.

Subsystem for Controlling the Curing Process Parameters

In some embodiments, a subsystem for controlling the curing processparameters (e.g., a controller) is provided to control operationalparameters for curing a CCM including controlling process stepsequences, durations and timing, and for logging data measured duringcuring operations. In various embodiments, the controller is incommunication with at least one of the source of carbon dioxide, the gasflow subsystem, the temperature control subsystem, and the humiditycontrol subsystem. In some embodiments, the controller is incommunication with sensors that provide data about the process, such astemperature, humidity, flow rates, gas pressures, gas compositions andthe like. The controller is configured to control independently at leasta respective one of the flow rate of the gaseous carbon dioxide, thecirculation of the gas through the curing chamber, the temperature ofthe gas, and the humidity in the gas during a time period when thematerial that consumes CO₂ as a reactant is being cured.

In general, each subsystem can be provided as a reusable module that canbe operationally connected to the other subsystems, for example usingconventional off-the-shelf mechanical and electrical connectors. In someembodiments, a complete control and operations system can then beprovided by assembling one or more modules of each type of subsystem asmay be required for a given curing operation. For curing procedures thatare expected to be carried out repeatedly, a complete control andoperations system can be provided as a unit. In the event that someportion of the control and operations system malfunctions, a relativelyexpeditious repair can be made by substituting an entire subsystem forthe malfunctioning component, and repair of that component can beconducted “off-line,” e.g., without significantly affecting the curingprocess for a given curing operation, so that the curing process can beaccomplished with only a minor deviation from the expected processduration. In particular, CCMs lend themselves to such correction oftemporary malfunctions, because the CCM simply stops curing when theconcentration of CO₂ is reduced sufficiently (e.g., when CO₂ is lackingin the curing gas). This is different from the curing of conventionalconcrete, which is initiated by the presence of water (H₂O), and whichin general cannot be interrupted once the conventional concrete mixturebecomes wet.

Turning now to FIG. 1, there is shown a schematic diagram of anembodiment of a curing system for use with CO₂ Composite Material. InFIG. 1 there is a gas conditioning system 102 and a curing chamber 120which are connected together by a gas delivery tube 140 and a gasrecovery tube 142. The gas conditioning system 102 includes elements ofeach of a source of carbon dioxide, a gas flow subsystem, a temperaturecontrol subsystem, a humidity control subsystem and a subsystem forcontrolling the curing process parameters. In the embodiment of FIG. 1,the gas delivery tube 140 and the gas recovery tube 142 can be anyconvenient size tabulation, for example a 6 inch diameter metal pipe. Agas source such as a CO₂ supply 130, and, as needed, sources of othergases such as air and/or water vapor are provided. The gas delivery andconditioning system can include a controller 116, such as a programmablelogic controller (PLC) or another microprocessor-based controller, suchas a general purpose programmable computer that can operate using a setof instructions recorded on a machine-readable medium. As illustrated inFIG. 1 a typical curing chamber 120 can include a plenum 122 that isconfigured to provide a gas atmosphere by way of one or more locationsat which gas can be injected into the curing chamber to create a gasflow 124 having desired properties such as flow velocity or flowpatterns in various portions of the curing chamber 120. The curingchamber in some embodiments will be as simple as an enclosure that cancontain a CCM to be processed and process gas with an inlet and anoutlet to allow the gas to be introduced and as needed removed.Additional details of such systems will be provided hereinafter.

FIG. 2 is a schematic diagram of an embodiment of an alternate curingsystem for use with CO₂ Composite Material. Many of the componentsillustrated in FIG. 2 can be the same as those shown in FIG. 1, butthere can be additional, or different, components. For example, both theembodiments of FIG. 1 and FIG. 2 use a number of thermocouples or othertemperature sensors (104, 104′, 104″, 104′″, 104″″, collectivelytemperature sensors 104) and a plurality of relative humidity sensors(106, 106′, collectively relative humidity sensors 106), which can befor example dry-bulb wet-bulb sensors that utilize the psychrometricratios for carbon dioxide and water vapor or dipole polarization watervapor measurement instruments or chilled mirror hygrometers orcapacitive humidity sensors.

As illustrated in FIG. 2, the CO₂ supply 130 can be connected to the CO₂inlet by way of different flow control pathways, such as valves 210,212, and 214 which may be used to provide a high flow rate, for exampleduring a purging cycle, or by way of valves 220, 222, flow controller224, and valve 226 which may be used to provide a more preciselycontrolled flow rate (typically having a slower flow rate than that usedin a purge cycle). In the embodiment shown in FIG. 2, the piping used toconnect the gas conditioning system 102 can be larger than that used inthe system illustrated in FIG. 1. For example, the piping can be 8 inchpipe. Another difference is the size of heaters used to heat the gasprovided to the curing chamber, which in FIG. 1 is illustrated as six1.3 kW heaters (114), while the heating system in FIG. 2 includeseighteen 1.8 kW heaters (214). As will be understood, in any particularsystem the precise capacities of the various components will be sized inrelation to the intended amount of material to be cured in the curingchamber 120.

The controller 116 can receive data from the temperature sensors 104 andthe relative humidity sensors 106, and can communicate bi-directionally(e.g., take data from and send commands to) the valves, the chiller (orcooler) 110, the chiller (or cooler) heat exchanger 112, the blower 108,the heaters (114, 214) and the CO₂ supply 130 so as to be able to logdata as a function of time, make determinations regarding the state ofcuring of a load in the curing chamber 120, and take corrective orpredetermined actions so as to control the curing process. Thecontroller 116 can also receive commands from a user, displayinformation to the user, and record data and the commands that may beissued from time to time so that a record of the curing process may beproduced in machine-readable form for later use.

Gas Flow in the Curing Chamber

The gas flow in the curing chamber in various embodiments can includegas flows external to the body, gas flows internal to the body, gasflows through a porous or pervious body, or combinations of such gasflows. The gas delivery system includes the gas delivery tube 140, thegas recovery tube 142, and the plenum 122, which can have many forms. Insome embodiments, the plenum 122 directs gases to the outside of greenbodies of CO₂ Composite Material. In other embodiments, the plenum 122directs gases to internal passages or openings in green bodies of CO₂Composite Material. In still other embodiments, the plenum 122 directsgases both to the outside of and to internal passages or openings ingreen bodies of CO₂ Composite Material.

Internal Gas Delivery System

This type of gas delivery system is comprised of linked, gridded pipinghaving a specific spacing and size, which delivers gas, or fluid througha series of holes distributed throughout the piping system, to asurrounding CO₂ Composite Material body. The supply of gas (includingcarbon dioxide) is then regulated to match or come close to matching thesequestration rate of CO₂ in the CO₂ Composite Material. This is onemethod to rapidly cure a section of CO₂ Composite Material. In thetypical internal gas delivery system, the piping system is left imbeddedin the CO₂ Composite Material sample after it is cured. The pipingsystem can act additionally as a means of reinforcement, and can providethe ability to perform cleaning or maintenance of CO₂ Composite Materialvia a compressed air or water backwashing technique.

Some of the benefits of this approach include but are not limited to areduction in cure time, reduction of carbon footprint associated with acast-in-place CO₂ Composite Material application, improved life ofpervious CO₂ Composite Material sections due to the ability to backwashdebris out of pervious CO₂ Composite Material and the presence of areinforcing grid. Standard practice for the placing of pervious concretewith Portland cement based systems calls for a 7-28 day curing periodbefore the area can be used. With the gas delivery system, finalstrength of a CO₂ Composite Material can be achieved in as little as 1day. In the trial outlined below a supply of CO₂ is regulated at 1.7 kgper hour. The result after 22 hours was a carbonation extent of 40% inrelation to the potential of the CO₂ Composite Material to carbonate.This correlates to 43% CO₂ efficiency. Based on this data, we cancontrol the gas supply rate to match the sequestration rate of the CO₂Composite Material thereby improving the efficiency of CO₂ usage andoptimizing the time needed to effect the curing process.

An embodiment of an internal gas delivery system for curing elongatespecimens such as railroad ties is now described.

FIG. 3 is a perspective view of a curing chamber suitable for curingelongate specimens of CO₂ Composite Material. The curing chamber in FIG.3 has a flexible wall 310 that is supported by frame members 320. Theclosure of flexible wall 310 may be accomplished by the use of weights,or by the use of magnetic stripping and magnetic frame members. Otherflexible wall systems are described in more detail hereinafter.

FIG. 4 is a view of the curing chamber of FIG. 3 containing an elongatespecimen 410 (a railroad tie) of CO₂ Composite Material to be cured.

FIG. 5 is a view of the curing chamber of FIG. 3 when closed to allowcuring to be performed. The flexible wall 310 is fully deployed in thisview.

In using a system as shown in FIG. 3 through FIG. 5, the process gas issupplied to at least one internal aperture that traverses the length ofthe CCM to be cured. The curing can then proceed from the inside of thegreen body toward the outside. Data has been obtained for such curingprocesses.

FIG. 6 is an image of a plenum used to deliver a curing atmosphere to asample of CO₂ Composite Material having an interior circular channel. Asmay be seen in FIG. 6, the plenum 610 is a pipe having a circular crosssection that can be placed in fluid communication with a circularchannel in a sample of CO₂ Composite Material to be cured.

FIG. 7 is an image of a sample 700 of CO₂ Composite Material that wascured using flow in an interior circular channel 710 and gas flow on theexterior of the sample. As shown in FIG. 7, the sample 700 has acircular region 720 that has been cured, a rectangular peripheral region730 that has been cured, and an uncured region 740 between the curedregions 720 and 730. This demonstrates the ability to cure the CCM fromthe inside using internal process gas flow and from the outside usinggas flow exterior to the sample.

FIG. 8 is an image that illustrates the difference in reaction depth asa function of flow rate. In FIG. 8 it is apparent that for the geometryexamined, a higher flow rate led to a greater depth of cure in the sametime interval.

FIG. 9 is a graph that illustrates the differences in reaction depth,gas flow in cubic feet per minute and amount of water removed fromspecimens of CO₂ Composite Material cured in systems using 1 fan and 3fans. It is apparent that reaction depth, gas flow in cubic feet perminute and amount of water removed from specimens of CO₂ CompositeMaterial all increase when more capacity to move the reactive gas isprovided.

FIG. 10 is a graph showing data for water removal rate as a function offlow rate for gases having different relative humidity. As is seen inFIG. 10, using a higher flow rate and a lower relative humidity tends toincrease the rate at which water is removed from the sample. It isbelieved that the reaction of CCM with CO₂ occurs preferentially at theinterface where water-saturated CCM is in contact with gaseous CO₂, somore rapid removal of water correlates with faster rates of cure.

Example—Cure Pervious Co₂ Composite Material in Place

The process of curing pervious CO₂ Composite Material in place is shownin FIG. 11 through FIG. 16. This is an installation that was made on theground to one side of a building. It is an example of a true outdoorcast in place application in use.

FIG. 11 is a process flow chart illustrating the steps in a process ofplacing and curing a composite material in an outdoor location. Theprocess can be divided into steps. In step 1110, one prepares the areawhere the CO₂ Composite Material is to be installed and cured. This caninclude digging, grading, setting out forms, and the like. In step 1120,one pours or otherwise installs a first layer of pervious CO₂ CompositeMaterial. The activity of installing the CO₂ Composite Material includesforming the body to be cured using any one or more of casting, pouring,vibrating, pressing, and the like, depending on the CO₂ CompositeMaterial formulation or mix workability.

In step 1130, one places or installs a gas delivery structure, which insome embodiments can be a tube or pipe with holes defined in a wallthereof. FIG. 12 is an image that illustrates a perforated PVC grid 1210used for gas delivery to a cast-in-place section of pervious CO₂Composite Material. The first layer 1220 of material to be cured is alsoseen, as can a gas connection point 1230.

In step 1140, one pours or installs a second (final) layer of perviousCO₂ Composite Material over the gas delivery structure. FIG. 13 is animage that illustrates pervious CO₂ Composite Material 1310 being pouredover the gas delivery system 1210 of FIG. 12. However, it should beunderstood that the installation of the gas delivery structure and thematerial to be cured at the desired location can be performed in anyorder, including placing the gas delivery structure in place first, andthen placing the material to be cured thereafter, or first placing thematerial to be cured and then installing the gas delivery structure.

In step 1150, one covers the installed material, for example with atarpaulin (a “tarp”) and one hooks up the gas line. FIG. 14 is an imagethat illustrates a section of pervious CO₂ Composite Material that iscovered with plastic sheeting 1410 and that has a CO₂ inlet 1420connected to gas connection point 1230.

Before the installed mixture is cured it may be necessary to dry orremove excess water from the uncured CO₂ Composite Material using one ormore of air drying, draining, or gas recirculation conditioning to getthe material to the proper conditions to begin the curing process. Insome embodiments, it may be necessary to add water to a dry mixture ofuncured CO₂ Composite Material.

In step 1160, one supplies gas to cure the CO₂ Composite Material. FIG.15 is an image that shows gas flow regulators and a flow meter used tocontrol the CO₂ supply to the pervious CO₂ Composite Material section ofFIG. 14. In FIG. 15, there are seen a high pressure regulator 1510, lowpressure regulator 1520, gas delivery piping 1530, a CO₂ mass flow meter1540, and a CO₂ mass flow meter readout 1550.

FIG. 16 is an image that shows a cured section of pervious CO₂ CompositeMaterial after 22 hours using the embedded CO₂ delivery system of FIG.12.

In some embodiments, sensors can be positioned within the volume of theCO₂ Composite Material to be cured so that operational parameters duringthe curing process may be monitored. Such sensors are in generalsacrificial or “one time use sensors” in that they are generally notremoved and recovered after the CO₂ Composite Material has been cured,but rather are permanently fixed in the CO₂ Composite Material.

Example: Cast-in-Place Curing System

A cast-in-place curing system involves systems and methods forcarbonating a CO₂ Composite Material in the absence of any sealedvessel. This “cast-in-place” curing technique involves the use of a gaspermeable barrier being used as a layer to allow CO₂ to diffuse througha cast section of CO₂ Composite Material. This is a procedure for rapidstrength generation and the permanent sequestration of carbon dioxidegas, leading to a reduction in the carbon footprint associated withcast-in-place concrete applications. This process is less energyintensive than all previous carbonation curing techniques as notemperature-controlled or sealed vessel is needed. It has beendemonstrated for the first time that a significant level of strength(+2,000 psi) can be achieved using the described cast-in-placetechniques with a dense CO₂ Composite Material.

CO₂ Composite Material has been carbonated via “bottom-up” carbonationcuring process. This trial involved successful carbonation without theuse of a sealed vessel to produce a CO₂ Composite Material slab havingcompressive strengths in excess of 2,000 psi.

We have used of Enkavent® material to create a gas permeable layer forproviding a larger CO₂ delivery surface to allow for carbonation in acast-in-place system.

FIG. 17 is a process flow chart illustrating the steps of placing andcuring CO₂ Composite Material using the cast-in-place process. In step1710 one prepares an Enkavent® layer with permeable coating bypositioning the material in the location where the CO₂ CompositeMaterial is to be cast and cured. In step 1720 one pours (or otherwiseplaces) the CO₂ Composite Material to be cast-in-place. In step 1730 oneconnects a curing system gas line in fluid communication with theEnkavent® layer. In step 1740 one starts the flow of gas into theEnkavent® layer. In step 1750 one supplies CO₂ gas to cure CO₂ CompositeMaterial for a time period long enough to effect the cure desired.

FIG. 18 is an image showing a mold 1800 that allows CO₂ delivery to andthrough Enkavent® material, in which the frame 1810 is arranged tocontain the CO₂ Composite Material in a desired size and shape. As seenin FIG. 18, the mold 1800 has a gas delivery line 1840 that introducesprocess gas below a porous screen 1830 that supports a layer ofEnkavent® material 1820. Enkavent® material is available from availablecommercially from Enka Geomatrix Systems, a Division of BASF Corporationof Enka, N.C., and its successor, Colbond, Inc. Enkavent® material isdescribed in more detail in U.S. Pat. Nos. 4,212,692, 5,960,595 and6,487,826. The CO₂ Composite Material is positioned adjacent theEnkavent® material.

FIG. 19 is an image showing uncured CO₂ Composite Material mix for usein a cast-in-place process.

FIG. 20 is an image showing a mold 1800 after casting a CO₂ CompositeMaterial and connection of the process gas line for curing the CO₂Composite Material with CO₂.

FIG. 21 is an image showing a section 2110 cut from a slab of CO₂Composite Material after carbonation curing.

Flexible-Wall Curing Chamber

Another type of curing chamber that can be employed to cure specimens ofCO₂ Composite Material is illustrated in FIG. 22 through FIG. 24. Thisis a chamber made from a flexible material, such as plastic sheetmaterial, to form a chamber having flexible walls. In a preferredembodiment the flexible material may be coated with a reflective layer,such as aluminum, so as to be reflective of infrared radiation. Similarmaterial is commonly used in blankets or ponchos used in human rescueoperations, or given to marathon runners at the end of a race so thatthe person's body heat can be more easily retained. In the embodimentsdescribed next, the wall is provided to contain a gas used in curingspecimens of CO₂ Composite Material placed within the chamber so thatthe properties of the gas, such as composition, temperature, relativehumidity and flow rate, can be controlled. In some embodiments, sensorsmay be situated within the chamber to provide data about the propertiesof the gas and the conditions within the chamber during a curingoperation.

FIG. 22 is a view of a curing chamber 2200 made of flexible material2210 that is attached to a rigid base 2220 by a clamping system. In oneembodiment, the flexible material is metalized plastic sheet. Othermaterials that can be used as the flexible material are Mylar® andlatex.

FIG. 23 is a view of the flexible material being installed to form thecuring chamber of FIG. 22.

FIG. 24 is a view of a clamping method for holding the flexible materialof the curing chamber of FIG. 22 to a rigid support. As illustrated inFIG. 24, a rigid base 2410 and a flexible sheet 2420 are connected bythe use of rigid rods 2430 and clamps 2440. In the embodiment shown therigid rods 2430 have square or rectangular cross sections. In someembodiments a deformable gasket 2450 may be placed between the matingsurfaces of the rigid base 2410 and the flexible sheet 2420 so as toprovide a more hermetic seal. The gasket 2450 can be any material thatis chemically compatible with the curing gas and that is sufficientlysoft so that it forms a substantially hermetic seal when compressedbetween the mating surfaces of the rigid base 2410 and the flexiblesheet 2420. Examples of such materials that can be used as gaskets areclosed cell plastic foam sheet and viscous liquids such as petroleumbased gels. In other embodiments, a channel filled with a liquid that iscompatible with the curing atmosphere, such as water, can be provided atthe location in which the mating surfaces of the rigid base 2410 and theflexible sheet 2420 are situated.

FIG. 25 is a view of another embodiment of a curing chamber 2500 havingsome flexible walls 2510 and some relatively rigid walls 2520. In theembodiment shown in FIG. 25, the aperture 2530 may be covered with amaterial that is transparent in a spectral region of interest, such asthe visible or the infrared, so that visual observations orinstrument-based electromagnetic radiation observations, such as opticalpyrometry or gas flow or gas composition measurements may be made. 2540is a fitting used to make a connection to a gas conditioning system 102as previously described (e.g., 2540 is used as the connection to one ofa gas delivery tube 140 and a gas recovery tube 142).

Modular Gas Handling System

FIG. 26 is a view of a modular gas handling system that can be used withvarious curing chambers.

FIG. 27 is a schematic diagram showing a gas handling system 2710 thathas multiple gas delivery ports 2730, 2730′, 2730″ and multiple gasrecovery ports 2740, 2740′, 2740″ by way of which it in fluidcommunication with a curing chamber 2720. The modular gas handlingsystem of FIG. 27 can be viewed as a multiple number of modular gashandling systems of FIG. 26 that operate in parallel under the controlof a controller. The gas handling system of FIG. 27 can be used toprovide gas flows having individually controlled flow rates, gascompositions and gas temperatures so that gas glows that are tailored tospecific regions of a single curing chamber can be provided andcontrolled. As needed, multiple sets of sensors can be provided so thateach gas flow stream can be individually monitored and controlled.

Computer-Based Control System

In order to control the operation of the curing system in a moreconvenient manner, there is provided at least one controller incommunication with at least one of the source of carbon dioxide, the gasflow subsystem, the temperature control subsystem, and the humiditycontrol subsystem. The at least one controller is configured to controlindependently during a time period when the material that consumes CO₂as a reactant is being cured at least a respective one of thecomposition of the gas provided for the curing process, the flow rate ofcarbon dioxide, the rate or velocity of circulation of the gas throughthe curing chamber or through the CCM being cured, the direction ofcirculation of the gas through the curing chamber, the temperature ofthe gas, and the humidity in the gas.

In a preferred embodiment, the controller is a general purpose computerthat is operated under a set of instructions recorded on amachine-readable medium, or a similar electronic device as described inmore detail hereafter. In some embodiments, an operator can control some(or all) of the operations in a curing process by overriding thecontroller, or by providing specific instructions to the controller thatare performed as the operator directs. For example, some of the steps ina curing process having to do with setting up the curing chamber,loading CCM material to be cured, unloading the cured material at theend of a curing cycle, and the like, may be more conveniently performedunder the control of a human operator. In many instances a humanoperator can take into consideration variations in the CCM materialsthemselves and how they are mechanically handled more easily than can apreprogrammed controller. After the preliminary steps are completed, thehuman operator can turn over control of the process to a controller,which can control the process for the duration of the curing time.Another benefit of using a controller is that the controller can recordand generate a log of the operational parameters that are set astargets, and can record the corresponding actual parameters that aremeasured during the curing process, so that the precision of the curingprocess can be increased over time by reprogramming the instructionsthat control a specific process to cause the actual measured operationalparameters to adhere more closely to the values that are set as targets.A well-known example of such improvement in control is the used ofproportional-integral-derivative (P-I-D) control when one is trying toset a change in a parameter that finally attains a steady state after atime interval, while attempting to minimize undershoot (too low a value)and overshoot (too high a value) as the desired steady state value isapproached.

FIG. 28 is a screenshot of a computer based control system for a curingchamber showing a schematic of the system to be controlled. In FIG. 28there is shown a schematic of the curing chamber 2810, components of thegas handling system 2820, a plurality of data windows 2830 for thedisplay of process parameters such gas compositions, temperature,pressure, relative humidity, blower speed or flow rates in real time,(e.g., in substantially the then current time as the process proceeds),a schematic of the CO₂ source 2840 and associated valves, and aschematic of a source of water/water vapor 2850.

FIG. 29 is a screenshot of a computer based control system for a curingchamber showing a number of components that can be controlled andshowing how parameter values that are measured can be displayed. Thescreenshot that is illustrated is a diagnostic panel in which aredisplayed the states 2910 of various components such as blowers,heaters, valves and the like, the desired or programmed values 2920 ofvarious operating parameters, such as temperature, relative humidity,percentage CO₂ and the like. The current measured values 2930 providedby various sensors, and a display 2940 of the step that is monitored(here “purge”) and some of the parameters that are being controlled. Thediagnostic information that is displayed may be different for differentsteps in the process.

FIG. 30 is a screenshot of a computer based control system for a curingchamber showing a recipe screen in which parameters for various periodsor steps in a curing process can be entered by a user or displayed to auser. As may be seen, the recipe screen can be used to enter individualsteps 3010 with their desired operating parameters. A set of “buttons”3020 is provided to allow a user to conveniently select different partsof a curing operation, such as control of gas compositions (e.g., abutton labeled “CO₂ control”), relative humidity conditions (e.g., abutton labeled “RH control”), operation of the controller itself (e.g.,a button labeled “PID control”) and many other parameters. There arealso provided buttons to save a recipe to a machine-readable medium ormemory, or to recall a previously saved recipe from memory. In someembodiments, the screen itself is a touchscreen. In some embodiments, apointing device such as a mouse may be used. In some embodiments, akeyboard, a numeric pad, and/or an “on screen” keyboard may be used inenter data or commands.

FIG. 31 is a screenshot image of an historical trend report for a curingoperation, showing a graph 3100 in which curve 3110 represents total CO₂consumed, curve 3120 represents relative humidity, and curve 3130represents temperature.

DEFINITIONS

Unless otherwise explicitly recited herein, any reference to anelectronic signal or an electromagnetic signal (or their equivalents) isto be understood as referring to a non-volatile electronic signal or anon-volatile electromagnetic signal.

Recording the results from an operation or data acquisition, such as forexample, recording results at a particular frequency or wavelength, isunderstood to mean and is defined herein as writing output data in anon-transitory manner to a storage element, to a machine-readablestorage medium, or to a storage device. Non-transitory machine-readablestorage media that can be used in the invention include electronic,magnetic and/or optical storage media, such as magnetic floppy disks andhard disks; a DVD drive, a CD drive that in some embodiments can employDVD disks, any of CD-ROM disks (i.e., read-only optical storage disks),CD-R disks (i.e., write-once, read-many optical storage disks), andCD-RW disks (i.e., rewriteable optical storage disks); and electronicstorage media, such as RAM, ROM, EPROM, Compact Flash cards, PCMCIAcards, or alternatively SD or SDIO memory; and the electronic components(e.g., floppy disk drive, DVD drive, CD/CD-R/CD-RW drive, or CompactFlash/PCMCIA/SD adapter) that accommodate and read from and/or write tothe storage media. Unless otherwise explicitly recited, any referenceherein to “record” or “recording” is understood to refer to anon-transitory record or a non-transitory recording.

As is known to those of skill in the machine-readable storage mediaarts, new media and formats for data storage are continually beingdevised, and any convenient, commercially available storage medium andcorresponding read/write device that may become available in the futureis likely to be appropriate for use, especially if it provides any of agreater storage capacity, a higher access speed, a smaller size, and alower cost per bit of stored information. Well known oldermachine-readable media are also available for use under certainconditions, such as punched paper tape or cards, magnetic recording ontape or wire, optical or magnetic reading of printed characters (e.g.,OCR and magnetically encoded symbols) and machine-readable symbols suchas one and two dimensional bar codes. Recording image data for later use(e.g., writing an image to memory or to digital memory) can be performedto enable the use of the recorded information as output, as data fordisplay to a user, or as data to be made available for later use. Suchdigital memory elements or chips can be standalone memory devices, orcan be incorporated within a device of interest. “Writing output data”or “writing an image to memory” is defined herein as including writingtransformed data to registers within a microcomputer.

“Microcomputer” is defined herein as synonymous with microprocessor,microcontroller, and digital signal processor (“DSP”). It is understoodthat memory used by the microcomputer, including for exampleinstructions for data processing coded as “firmware” can reside inmemory physically inside of a microcomputer chip or in memory externalto the microcomputer or in a combination of internal and externalmemory. Similarly, analog signals can be digitized by a standaloneanalog to digital converter (“ADC”) or one or more ADCs or multiplexedADC channels can reside within a microcomputer package. It is alsounderstood that field programmable array (“FPGA”) chips or applicationspecific integrated circuits (“ASIC”) chips can perform microcomputerfunctions, either in hardware logic, software emulation of amicrocomputer, or by a combination of the two. Apparatus having any ofthe inventive features described herein can operate entirely on onemicrocomputer or can include more than one microcomputer.

General purpose programmable computers useful for controllinginstrumentation, recording signals and analyzing signals or dataaccording to the present description can be any of a personal computer(PC), a microprocessor based computer, a portable computer, or othertype of processing device. The general purpose programmable computertypically comprises a central processing unit, a storage or memory unitthat can record and read information and programs using machine-readablestorage media, a communication terminal such as a wired communicationdevice or a wireless communication device, an output device such as adisplay terminal, and an input device such as a keyboard. The displayterminal can be a touch screen display, in which case it can function asboth a display device and an input device. Different and/or additionalinput devices can be present such as a pointing device, such as a mouseor a joystick, and different or additional output devices can be presentsuch as an enunciator, for example a speaker, a second display, or aprinter. The computer can run any one of a variety of operating systems,such as for example, any one of several versions of Windows, or ofMacOS, or of UNIX, or of Linux. Computational results obtained in theoperation of the general purpose computer can be stored for later use,and/or can be displayed to a user. At the very least, eachmicroprocessor-based general purpose computer has registers that storethe results of each computational step within the microprocessor, whichresults are then commonly stored in cache memory for later use, so thatthe result can be displayed, recorded to a non-volatile memory, or usedin further data processing or analysis.

Theoretical Discussion

Although the theoretical description given herein is thought to becorrect, the operation of the devices described and claimed herein doesnot depend upon the accuracy or validity of the theoretical description.That is, later theoretical developments that may explain the observedresults on a basis different from the theory presented herein will notdetract from the inventions described herein.

While the present invention has been particularly shown and describedwith reference to the preferred mode as illustrated in the drawing, itwill be understood by one skilled in the art that various changes indetail may be affected therein without departing from the spirit andscope of the invention as defined by the claims.

What is claimed is:
 1. A controller, comprising: a microprocessorconfigured to operate under control of a set of instructions recorded ona first machine-readable medium, said microprocessor when operatingunder said set of instructions performing: controlling operation of atleast one of a source of carbon dioxide, a gas flow subsystem, atemperature control subsystem, and a humidity control subsystem; flowinga process gas containing carbon dioxide so as to contact a material tobe cured by reaction with said carbon dioxide in said process gas, andcuring the material by the reaction with carbon dioxide; monitoring atleast one parameter selected from a group of monitored parametersconsisting of an elapsed time from said instituting of said flow, acarbon dioxide concentration, a relative humidity, a flow rate, atemperature, and a pressure of said process gas as said process gas isbeing provided; and performing at least one of: recording said at leastone parameter, transmitting said at least one parameter to a datahandling system, or to displaying said at least one parameter to a user.2. The controller of claim 1, wherein said microprocessor when operatingunder said set of instructions receives a start command from an externalsource.
 3. The controller of claim 1, wherein said microprocessor whenoperating under said set of instructions determines a state of cure ofsaid material to be cured by reaction with said carbon dioxide.
 4. Thecontroller of claim 1, wherein said microprocessor when operating undersaid set of instructions monitors at least one parameter selected fromthe group of parameters consisting of a carbon dioxide concentration, arelative humidity, a flow rate, a temperature, a pressure, and a flowduration of said process gas as said process gas is removed from contactwith said material to be cured by reaction with said carbon dioxide. 5.The controller of claim 1, wherein said microprocessor when operatingunder said set of instructions monitors at least one parameter selectedfrom the group of parameters consisting of a carbon dioxideconcentration, a relative humidity, a flow rate, a temperature, and apressure at one or more locations within a curing chamber.
 6. Thecontroller of claim 1, wherein said gas flow subsystem comprises: atleast one of a valve, a flow regulator, a mass flow controller, ablower, and a gas delivery structure; said gas flow subsystem configuredto provide a process gas comprising carbon dioxide as a reagent in fluidcontact with a material to be cured by reaction with said carbondioxide.
 7. The controller of claim 1, wherein said gas flow subsystemis compatible with water vapor in addition to said process gascomprising carbon dioxide as a reagent.
 8. The controller of claim 1,wherein said gas delivery structure is a gas permeable layer placedadjacent the material to be cured by reaction with said carbon dioxide.9. The controller of claim 1, wherein said temperature control subsystemcomprises: at least a selected one of a heater and a cooler, saidtemperature control subsystem configured to control a temperature of aprocess gas containing carbon dioxide so as to cause said process gas toattain a desired temperature prior to coming into contact with amaterial to be cured by reaction with said carbon dioxide in saidprocess gas.
 10. The controller of claim 1, wherein said humiditycontrol subsystem comprises: at least a selected one of a water vaporsource and a water vapor removal apparatus, said humidity controlsubsystem configured to control a humidity of a process gas containingcarbon dioxide so as to cause said process gas to attain a desiredhumidity prior to coming into contact with a material to be cured byreaction with said carbon dioxide in said process gas.